Innerboot for a sports boot

ABSTRACT

A removable innerboot of a sports boot, the wall of which innerboot comprises a rear part ( 3 ) which is stiffer than a front part ( 4 ), wherein the wall of the innerboot comprises at least one layer comprising in its stiffer rear part ( 3 ) a first element located alongside a more flexible second element of its front part ( 4 ), these two elements being fastened together by an edge-to-edge seam ( 5 ).

BACKGROUND OF THE INVENTION

The invention relates to a removable innerboot for a sports boot, particularly suitable for boots for gliding boards such as ski, snowboard or for skating boots. It also relates to the method of manufacturing the upper of such an innerboot and the method of manufacturing such an innerboot.

DESCRIPTION OF THE PRIOR ART

Innerboots for ski boots of the prior art comprise an upper or vamp extending vertically above a horizontal sole. One method of manufacturing such an innerboot consists in producing a flat plastic blank and then shaping it in order to obtain a three-dimensional upper. A foam for comfort is generally added on the inside of the wall of the upper and a sole is fastened in the lower area thereof in order to form the final innerboot. This method has the advantage of great simplicity and low cost. Its drawback is that it forms an innerboot of uniform structure which is poorly suited to the anatomy of the foot. Moreover, the plastic forming the innerboot must be stiff in order for the innerboot as a whole to retain satisfactory integrity while it is being fitted. However, this stiffness is unnecessary and reduces the comfort of the innerboot in certain areas such as the front part of the upper.

In order to alleviate the abovementioned drawbacks, another method consists in manufacturing what is known as a “composite” innerboot comprising a number of separate foam elements having different properties joined together on the flat blank of the upper in order to obtain a more comfortable result since it is closer to the anatomy of the foot. These different foam elements may be located alongside one another within the wall of the innerboot and/or be superposed on one another. Similarly, stiff wall elements may be superposed on the rest of the wall, on the outer face thereof, and be fastened by any known means in order to stiffen the wall in certain areas. Generally, a stiff element is added in the rear part of the innerboot, in particular around the heel, in order for it to achieve satisfactory integrity while it is being fitted. One drawback of such a solution is its high cost since it requires the superposition of several layers of material which entails high consumption of materials and due to the fashioning of all the independent parts which form the innerboot. A second drawback is that the structure obtained is not very satisfactory since the different foam elements are positioned, for example, in a very imprecise manner. Finally, a last drawback is that it entails overthicknesses where certain elements are superposed and this can cause hard, painful points at the boundaries between several superposed stiff elements.

There thus exists a need for a novel structure for a sports boot innerboot that does not have the abovementioned drawbacks.

SUMMARY OF THE INVENTION

More precisely, an object of the invention consists in providing a comfortable solution for a removable sports boot innerboot, the method of manufacturing which remains economical.

According to the concept of the invention, the removable innerboot for a sports boot has a wall comprising a rear part which is stiffer than a front part, wherein the wall of the innerboot comprises at least one layer comprising in its stiffer rear part a first element located alongside a more flexible second element of its front part, these two elements being fastened together by an edge-to-edge seam.

The invention is defined more precisely by the claims.

DESCRIPTION OF THE DRAWINGS

These objects, features and advantages of the present invention will be presented in detail in the following description of a particular nonlimiting embodiment in relation to the attached figures, in which:

FIG. 1 is a perspective side view of an innerboot according to one embodiment of the invention;

FIG. 2 is a perspective side view of an innerboot according to a variant of the embodiment of the invention;

FIG. 3 shows a flat blank according to a step of manufacturing an upper of an innerboot according to the embodiment of the invention; and

FIG. 4 shows the flat blank covered with a foam according to another step of manufacturing an upper of an innerboot according to the embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention concerns the structure of the wall of an innerboot. The outermost surface of the wall of the innerboot in contact with the outside and intended to come into contact with the inner face of a stiff shoe upper into which the removable innerboot will be inserted will be referred to as the outer face, and, by contrast, the surface intended to come into contact with a user's foot is the inner surface of the innerboot. In addition, the wall of the innerboot seen in cross section, i.e. in a direction perpendicular to the surface of the innerboot and running from the outside to the inside of the innerboot, is composed generally of a plurality of elements forming in this way a plurality of superposed layers fastened together inseparably. The expression “superposition” will therefore be used for these elements positioned one on another in a direction transverse to the wall of the innerboot. In addition, viewing the wall of the innerboot in section in a plane parallel to the wall of the innerboot and perpendicular to a cross-sectional plane, enables the structure of one layer of the innerboot wall, at a certain thickness of its wall, to be shown, and where relevant will also enable various elements positioned alongside one another in this same innerboot wall layer to be shown. The expression “alongside one another” will therefore be used for these various elements positioned within one layer. It should be noted that two separate elements in the wall of an innerboot may be both superposed in certain parts of the innerboot wall and located alongside one another in other parts of the innerboot. These definitions will help to clarify the following description of the invention.

According to an essential element of the invention, the upper of the comfort innerboot comprises a wall which is stiffer in its rear part than in its front part, in order both to provide the user with good heel support and better comfort for the front part of the foot. This property is obtained by producing at least one layer of the wall of the upper which comprises two elements of differing stiffness located alongside one another and fastened together by an edge-to-edge seam. This edge-to-edge seam enables these two elements to be located precisely alongside one another and not superposed, this having the advantage of preventing hard points that may be painful and would be obtained if these two elements were partially superposed where they are fastened together. According to one possible variant embodiment, a sealing element, for example adhesive, may be provided on the inner or outer face of the layer comprising the edge-to-edge seam such that the leaktightness of the innerboot is improved at this edge-to-edge seam.

FIG. 1 illustrates such an innerboot, thus comprising an upper 1 and a sole 2, the upper comprising a rear part 3 which is stiffer than a front part 4. For this purpose, the wall of the upper comprises an outer layer in contact with the outside and comprising a first element in its rear part 3 and a more flexible second element in its front part 4, these two elements being located alongside one another in the outer layer of the innerboot wall and connected by an edge-to-edge seam 5. Next, this wall of the innerboot upper may be completed by other superposed layers comprising other elements such as a foam and an inner comfort fabric, according to any technique of the prior art.

The boundary comprising the edge-to-edge seam 5 between the rear part 3 and the front part 4 may form a substantially vertical line, as illustrated in FIG. 1, or may alternatively have any other form, possibly curved, such as is illustrated, for example, in FIG. 2. These different production variants represent different surface areas of rigid material in the rear part of the heel which correspond to different compromises between the comfort of the innerboot and its performance. Specifically, comfort is increased if the surface area of the more flexible front part is as large as possible. On the other hand, the performance of the innerboot for sports purposes is increased if the surface area of the stiffer rear part is as large as possible since the stiffer wall is better able to transmit the forces exerted by the user. Thus, it is possible to envision an innerboot for a beginner in which the surface area of the rear part is very small in order to increase comfort, and, at the opposite end of the scale, a competition innerboot in which the surface area of the rear part is very large in order to achieve the best possible performance.

FIGS. 3 and 4 illustrate a method of manufacturing an innerboot upper according to one advantageous embodiment of the invention.

The first step consists in cutting out a flat blank 11 such as is illustrated schematically in FIG. 3, the shape of which enables the desired three-dimensional upper to be obtained once it has been shaped according to a method known from the prior art. According to the invention, this flat blank 11 is formed by joining together three elements by edge-to-edge seams 15, a central element 13 and two side elements 14, this central element 13 being stiffer than the two side parts 14. This blank 11 obtained in such a way is intended to form an outer layer of the wall of the upper. It may possibly be subsequently covered at least partially with another outer layer, in which case it no longer forms the outer layer of the wall.

In the case where the two elements of differing stiffnesses connected by an edge-to-edge seam are located on the outer layer of the wall of the boot, the seam 15 can be seen from outside the innerboot and the two elements 13, 14 fastened together by this seam may be selected to have different colors to augment the esthetic nature of the assembly obtained and to emphasize the technical function implemented by this innerboot structure.

The different elements 13, 14 forming this blank 11 can be plastics, for example PVC, having different stiffnesses. By way of example, the stiffer element 13 may have a thickness of between 3 and 3.5 millimeters, and be made of nylon coupled with polyethylene and EVA, having a stiffness represented by a Shore A value close to 50, preferably between 40 and 70 Shore A. Thus, this stiffer rear element will advantageously have a large thickness of between 2.5 and 4 millimeters while the more flexible element 14 will have a conventional, thinner structure, for example around 1.5 millimeters. The stiffer material advantageously has sufficient stiffness to fulfill the technical function of innerboot integrity, i.e. to enable it to retain its vertical integrity while it is being fitted, during which phase the user's foot tends to squash its structure downward. These elements thus have a thickness of several millimeters and their being joined together by an edge-to-edge seam prevents hard points as could be caused by other types of seam fastening, such as a seam requiring them to be superposed at least on a seam strip.

The second step of manufacturing the upper consists in adding a superposed foam comfort layer intended to be located toward the inside of the finished innerboot, contacting directly or indirectly, via an inner fabric, a user's foot.

According to one advantageous embodiment of the invention, this foam layer is obtained by a first substep of bonding at least one foam of the agglomerated type, obtained by recycling and aggregating various foam elements. The foam may occupy virtually the whole surface area of the flat blank, either superposed on the central element 13 or extending over all the elements 13, 14. Alternatively, several separate foam elements can be fastened to the blank 11, such that they are superposed or located alongside one another. Subsequently, the added foam is subjected to a second machining substep following its fastening, for example by milling or grinding, in order to obtain different thicknesses in different areas of the blank 11. This step of machining the foam after it has been fastened to a flat element enables the various areas of different thicknesses of the foam to be defined with great precision, much more than with the prior art method of bonding separate elements of which the final geometry has been produced separately beforehand. Thus, a blank obtained in such a way is illustrated in FIG. 4 which shows very thick areas of foam 16 within which are slightly less thick areas in the form of flat disks 17, corresponding to the locations of the user's two ankle bones. Subsequently, the thickness of the foam decreases continuously toward the periphery of the blank 11.

Alternatively, the layer or layers of foam could be formed by injection molding or thermocompression.

Finally, an inner fabric, also known as an inner lining, can be superposed on the foam to form the future inner layer of the innerboot, intended to come into contact with the user's foot.

A third method step consists, finally, in shaping the flat blank 11 to give it its three-dimensional shape. The two side elements 14 are, for example, connected to form the front part 4 of the three-dimensional upper, this front part being more flexible than its rear part 3.

Finally, a sole 2 is fastened to this finished upper to obtain a removable innerboot of a sports boot.

Of course, variant embodiments may remain within the scope of the invention. Thus, it is possible to envision an innerboot wall structure comprising more than two or three elements located alongside one another on a layer of the innerboot wall and connected by edge-to-edge seams. In addition, the edge-to-edge seam between these elements of different stiffnesses may be obtained within a layer of the wall of the upper other than the outer layer. The edge-to-edge seams of the two side parts of the innerboot may have a symmetric or asymmetric geometry. This is because the side corresponding to the inner part of the foot, facing the other foot, is subjected to more force than the other side and it is conceivable to opt for a larger surface area of stiffer material on this inner side wall than on the outer side wall, and this results in an edge-to-edge seam that is overall further forward on the inner wall of the innerboot. 

1. A removable innerboot of a sports boot, the wall of which innerboot comprises a rear part (3) which is stiffer than a front part (4), wherein the wall of the innerboot comprises at least one layer comprising in its stiffer rear part (3) a first element located alongside a more flexible second element of its front part (4), these two elements being fastened together by an edge-to-edge seam (5).
 2. The sports boot innerboot as claimed in claim 1, wherein the layer of the innerboot wall comprising the two elements fastened together by an edge-to-edge seam (5) is the outer layer of the innerboot wall.
 3. The sports boot innerboot as claimed in claim 1, wherein the two elements fastened together by an edge-to-edge seam are two plastics having different stiffnesses.
 4. The sports boot innerboot as claimed in claim 1, wherein the stiffer first element of the rear part has a large thickness of between 2.5 and 4 millimeters.
 5. The sports boot innerboot as claimed in claim 4, wherein the more flexible second element of the front part has a thickness of less than 2 millimeters.
 6. The sports boot innerboot as claimed in claim 1, wherein the edge-to-edge seam (5) between the two elements is substantially vertical or has curves.
 7. The sports boot innerboot as claimed in claim 1, wherein the innerboot wall further comprises a layer of machined foam superposed on at least one area of at least one of the two elements of the innerboot wall which are located alongside one another and fastened together by an edge-to-edge seam (5).
 8. A method of manufacturing an upper of a removable innerboot of a sports boot, which comprises a step in which a flat blank (11) is formed comprising the fastening by an edge-to-edge seam (15) of at least two different elements (13, 14) of different stiffness, the stiffer element (13) being intended to be positioned in the rear part of the upper.
 9. The method of manufacturing an upper (1) of a removable innerboot of a sports boot as claimed in claim 8, which comprises the formation of a flat blank intended to form an outer layer of the upper, this flat blank comprising a central element (13) intended to form the rear part of the innerboot upper and two more flexible side elements (14) intended to form the front part of the innerboot upper, these two side elements (14) being fastened to the central element (13) by an edge-to-edge seam (15).
 10. The method of manufacturing an upper of a removable innerboot of a sports boot as claimed in claim 8, which further comprises a step consisting in fastening a foam element on the flat blank (11) and in machining this foam element after it has been fastened in order to give it a varied shape (16, 17) suited to the anatomy of a foot.
 11. The method of manufacturing an upper of a removable innerboot of a sports boot as claimed in claim 8, which comprises a step of shaping the flat blank (11) in order to form the three-dimensional upper (1).
 12. A method of manufacturing a sports boot innerboot, which comprises manufacturing an upper (1) as claimed in claim 11 followed by a step of fastening a sole (2) to the upper. 